Chemical ecology
Chemical ecology examines the role of chemical interactions between living organisms and their environment, as the consequences of those interactions on the ethology and evolution of the organisms involved. It is thus a vast and highly interdisciplinary field.[1] Chemical ecology studies focuses on the biochemistry of ecology and the specific molecules or groups of molecules termed semiochemicals that function as signals to initiate, modulate, or terminate a variety of biological processes such as metabolism. Molecules that serve in such roles typically are readily diffusible organic substances of low molecular mass that derive from secondary metabolic pathways, but also include peptides. Chemical ecological processes mediated by semiochemicals may be intraspecific (occurring within a species) or interspecific (occurring between species).[2]
The field relies on analytical and synthetic chemistry, protein chemistry, genetics, neurobiology, ecology, and evolution.[3]
Contents
Chemical Ecology of Plants[edit]
Chemical ecology in plants is the study that integrates the chemistry and biological properties of the plants and its interaction with the environment (i.e. microorganisms, phytophagous insects) and their antagonists. Chemical ecology in plants mainly focuses on how plants fight against herbivory by producing various phytochemical compounds. This results from the chemistry of the plants and also various chemical relationships that plants with other subgroups such as fungi and bacteria through various symbiotic relationships.[4]
The surface of the primary aerial parts of terrestrial plants is covered by a thin waxy structure known as the cuticle, which has the crucial autecological functions and also plays an important role as an interface in trophic interactions. The cuticle is composed of the cuticular layer and the cuticle proper, which is covered by epicuticular waxes. Whereas the cutin fraction is a polyester-type biopolymer composed of hydroxyl and hydroxy epoxy fatty acids, the cuticular waxes are a complex mixture of long-chain aliphatic and cyclic compounds. These highly lipophilic compounds determine the hydrophobic quality of the plant surface and together with the microstructure of the waxes, vary in a species-specific manner. The physiochemical characteristics contribute to certain optical features, limit transpiration and influence adhesion of particles and organisms, and as a result prevents it from undergoing wilting. Apart from that the cuticle acts like a skin for plants which prevents any mechanical damage to them from the external sources which either living organisms or any other abiotic component.[5]
There are various ways in which chemical ecology can be evidenced in plants, such as the relationship between fungi and plants is called mycorrhizae. Fungi produces a chemical which decomposes organic matter to which enable the plant roots to increase its surface area to obtain to those nutrients through the help of the root hairs. [6]
Interactions with Microorganisms[edit]
The most important thing that makes it possible for microorganisms to interact with the plants is their ability to establish themselves on the plants surface. In order for the living organisms to establish onto the surface of the plants they need to break the hydrophobic layer of the plant. To do this, the microorganisms secrete special fluids which break down the fats from the cuticle. As a result they are able to establish themselves over the surface.[5]
Growth in Plants[edit]
Most of the hormones in plants are concentrated on their tips. The auxin hormones are responsible for growth of plants and are stimulated by certain stimulus such as light. This phenomenon is called phototropism. This growth enables the plant to obtain essentials such as sunlight which is very necessary for the photosynthesis. Therefore, the cuticle is one of the fundamental parts of the plant due to its physical and chemical properties such as waxy and thin like structure that enables it to be adapted to various mechanism such as hydrophobicity, interactions with microorganisms and growth of plants.[7]
Plant-Insect Interaction[edit]
The chemical ecology of plant-insect interaction is a significant subfield of chemical ecology.[8][9] In particular, plants and insects are often involved in a chemical evolutionary arms race. As plants develop chemical defences to herbivory, insects which feed on them evolve immunity to these poisons, and in some cases, re-purpose these poisons for their own chemical defence against predators. One of the more well-known examples of this is the monarch butterfly, the caterpillars of which feed on the milkweed plant. Milkweeds contain cardenolide toxins, but monarch butterfly caterpillars have evolved to remain unaffected by the toxin. Instead, they sequester the toxins during their larval stage and the poison remains in the adult, making it unpalatable to predators. Many other such examples of this exist, including Manduca sexta (hawkmoth) caterpillars which actively sequester nicotine found in the tobacco plant;[8] and the Bella moth, which secrets a quinone-containing froth from its head when disturbed by a potential predator obtained from feeding on Crotalaria species as a caterpillar.
Marine Chemical Ecology[edit]
Marine Chemical Ecology is how organic life in the marine environment use chemicals to eat, interact, reproduce and survive, ranging from microscopic phytoplankton to the many species of crustaceans, sponges, coral and fish.
Defence[edit]
The use of chemicals are often used a means of survival for marine organisms. Some crustaceans and mesograzers use particular algae and seaweeds as a means of deterrence by covering their bodies in the these plants. These plants produce alcohols such as pachydictyol-A and dictyol-E, which prevent the predation of the crustacean. When this seaweed is absent, or another seaweed without these alcohols are worn, the rate that these crustaceans are eaten is much higher. Other crustaceans use their natural defences in conjuncture with produced chemicals to defend themselves. Chemicals within their urine help coordinate them into groups. This combined with their spikes make them a much harder target for predators[10]. Others secrete mucus or toxins that make it difficult for predators to eat them, such as the Pardachirus marmoratus that use a toxin capable of paralyzing the jaws of a would-be predator. Simply being a certain colour can serve as a defence mechanism, such as some zoanthids displaying a wide range of colours. This suggests that they may be toxic to eat, whether they are or not.[11]
Reproduction[edit]
The release of chemicals are very important to coordinate marine organisms to reproduce. Some processes are relatively simple, such as attracting one individual to another. Male lampreys attract ovulating females by emitting a bile that can be detected many metres downstream. Other processes can be more complex, such as the mating habits of crabs. Due to the fact that mating can only be done shortly after the female moults from her shell, pheromones are produced before and after the moulting process. Male crabs will find and defend the potential mate until the shell has moulted. However due to the cabalistic tendencies of crabs, an additional pheromone is produced to suppresses this urge.[10]
Dominance[edit]
Determining dominance among crustaceans are very closely tied to chemical cues. When crustaceans fight to determine dominance they release urine, which helps to determine the victor. After a fight as concluded both individuals will recognize each other in the future through urine, remembering who is the dominant of the two and thereby avoiding a fight. This can also have an impact on future fights. When an individual is exposed to the urine of a dominant crustacean they will act more submissive, and the opposite effect when they are exposed to the urine of a subdominant individual. When individuals are unable to communicate through urine fights can be more unpredictable, resulting in longer fights.[10]
See also[edit]
- Chemical defense
- Pheromone
- May R. Berenbaum
- Lincoln Brower
- Thomas Eisner
- Jerrold Meinwald
- Wendell L. Roelofs
References[edit]
- ^ "What is Chemical Ecology? | CHEMICAL ECOLOGY". NCBS. Retrieved 2017-12-10.
- ^ Law, JH; Regnier, FE (1971). "Pheromones". Annual Review of Biochemistry. 40: 533–548. doi:10.1146/annurev.bi.40.070171.002533.
- ^ Meinwald, J.; Eisner, T. (19 March 2008). "Chemical ecology in retrospect and prospect". Proceedings of the National Academy of Sciences. Proceedings of the National Academy of Sciences. 105 (12): 4539–4540. doi:10.1073/pnas.0800649105. ISSN 0027-8424.
- ^ Dyer, Lee A.; Philbin, Casey S.; Ochsenrider, Kaitlin M.; Richards, Lora A.; Massad, Tara J.; Smilanich, Angela M.; Forister, Matthew L.; Parchman, Thomas L.; Galland, Lanie M. (2018-05-25). "Modern approaches to study plant–insect interactions in chemical ecology" (PDF). Nature Reviews Chemistry. 2 (6): 50–64. doi:10.1038/s41570-018-0009-7. ISSN 2397-3358.
- ^ a b Müller, Caroline; Riederer, Markus. "Plant Surface Properties in Chemical Ecology" (PDF). Journal of Chemical Ecology. 31 (11). doi:10.1007/s10886-005-7617-7.pdf. ISSN 0098-0331.
- ^ "Memorial University Libraries - Proxy Login". pubs-rsc-org.qe2a-proxy.mun.ca. Retrieved 2018-11-18.
- ^ Sondheimer, Ernest (2012-12-02). Chemical Ecology. Elsevier. ISBN 9780323154666.
- ^ a b Mithfer, Axel; Boland, Wilhelm; Maffei, Massimo E., "Chemical Ecology of Plant–Insect Interactions", Molecular Aspects of Plant Disease Resistance, Wiley-Blackwell, pp. 261–291, doi:10.1002/9781444301441.ch9, ISBN 9781444301441, retrieved 2018-08-21
- ^ Dyer, Lee A.; Philbin, Casey S.; Ochsenrider, Kaitlin M.; Richards, Lora A.; Massad, Tara J.; Smilanich, Angela M.; Forister, Matthew L.; Parchman, Thomas L.; Galland, Lanie M. (2018-05-25). "Modern approaches to study plant–insect interactions in chemical ecology". Nature Reviews Chemistry. 2 (6): 50–64. doi:10.1038/s41570-018-0009-7. ISSN 2397-3358.
- ^ a b c Hay, Mark E. (2009). "Marine Chemical Ecology: Chemical Signals and Cues Structure Marine Populations, Communities, and Ecosystems". Annual Review of Marine Science. 1: 193–212. ISSN 1941-1405. PMC 3380104. PMID 21141035.
- ^ Bakus, Gerald J.; Targett, Nancy M.; Schulte, Bruce. "Chemical ecology of marine organisms: An overview" (PDF). Journal of Chemical Ecology. 12 (5). doi:10.1007/bf01638991.pdf. ISSN 0098-0331.
Further reading[edit]
- Berenbaum MR & Robinson GE (2003). "Chemical Communication in a Post-Genomic World [Colloquium introductory article]". Proc. Natl. Acad. Sci. U.S.A. 100 (Suppl 2, November 25): 14513. Bibcode:2003PNAS..10014513B. doi:10.1073/pnas.2335883100. PMC 304109.
- Wajnberg, Eric; Colazza, Stefano (2013). Chemical Ecology of Insect Parasitoids. Blackwell. ISBN 978-1118409527.
- Putnam, A. R. (1988). "Allelochemicals from Plants as Herbicides" Weed Technology. 2(4): 510-518.
External links[edit]
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- A new antibiotic in African ants putatively protective of insect-fungi symbiosis through control of bacterial infections
- Insect Olfaction of Plant Odour
- International Society of Chemical Ecology
- "Search: Chemical ecology reviews". PubMed. U.S. National Library of Medicine.
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